1. Field of the Invention
The present invention relates to methods and devices for testing substrate materials, and more particularly, to methods and devices for testing semiconductor packaging materials.
2. Description of the Related Art
The use of build-up organic substrates for semiconductor packaging, such as flip chip plastic ball grid array (FCPBGA), is increasing. One area in which FCPBGA is being applied is the area of high power processors. Typical applications for FCPBGA involve processor chips with a power requirement of 45 watts or less. Recent applications requiring chips up to 100 W, and applications under development requiring power in excess of 200 W, have raised concerns about the reliability of the organic build-up laminate substrates used for chip packaging.
Typically thermal evaluations of high power chips are accomplished by fabricating high resistance heaters in the chip, so that a low amount of current can be used to power the heaters and thereby control the amount of heat generated by the chip. Such an approach does not satisfy the concerns raised for high power applications because the low amount of current needed to heat the chip is not representative of the currents that may pass through laminates of chips and interconnects in actual high power applications.
Because of this use of chips in high power applications, there is a significant effort to cool chips and interconnects to a specified temperature, typically 85° C. or lower. However, passing high current through fine conductive copper features in the laminate can potentially add more heat to the packaging laminate under the chip due to resistive heating.
Therefore, there is a need to provide a device and method to determine effects on characteristics of substrates used in packaging high power chips. Such characteristics include additional heating occurring inside the organic packaging substrate as a result of resistive heating of the conductive features when high currents are passed through the conductive features. Other characteristics include the long term reliability of the organic laminate making up the packaging, as it is subjected to these high currents for extended periods of time, and the long term reliability effects of having the organic laminate subjected to repeated heating and cooling experienced during on-off power cycles. The present invention addresses these needs.